outputs support in the action

README.md

@@ -209,3 +209,28 @@ yq e '.a.b | length' f1.yml f2.yml
 
 ## Known Issues / Missing Features
 - `yq` attempts to preserve comment positions and whitespace as much as possible, but it does not handle all scenarios (see https://github.com/go-yaml/yaml/tree/v3 for details)
+
+## GitHub Action
+
+If we want to use the yq action to look up a value from within a YAML file inside the repo, we can do this:
+
+```yml
+      - uses: actions/checkout@v2
+      - name: Get SDK Version from config
+        id: lookupSdkVersion
+        uses: mikefarah/yq@master
+        with:
+          cmd: yq eval '.renutil.version' 'config.yml'
+      - name: Restore Cache
+        id: restore-cache
+        uses: actions/cache@v2
+        with:
+          path: ../renpy
+          key:  ${{ runner.os }}-sdk-${{ steps.lookupSdkVersion.outputs.result }}
+          restore-keys: |
+            ${{ runner.os }}-sdk
+      # ... more
+```
+You can even lookup how the GitHub action [itself is configured](https://github.com/mikefarah/yq/issues/844#issuecomment-856700574)
+
+If you [enable step debug logging](https://docs.github.com/en/actions/managing-workflow-runs/enabling-debug-logging#enabling-step-debug-logging), you can see additional information about the exact command sent as well as the response returned within the GitHub Action logs.

action.yml

@@ -1,11 +1,15 @@
 name: 'yq - portable yaml processor'
 description: 'create, read, update, delete, merge, validate and do more with yaml'
+branding:
   icon: command
   color: gray-dark
 inputs:
   cmd:
     description: 'The Command which should be run'
     required: true
+outputs:
+  result:
+    description: "The complete result from the yq command being run"
 runs:
   using: 'docker'
   image: 'github-action/Dockerfile'

github-action/entrypoint.sh

@@ -1,4 +1,6 @@
 #!/bin/sh -l
 
-echo "$1"
+echo "::debug::\$cmd: $1"
-eval $1
+RESULT=$(eval "$1")
+echo "::debug::\$RESULT: $RESULT"
+echo ::set-output name=result::"$RESULT"